Abstract: The present study aimed to expand the current conceptualized relation between hostile experiences and hostile attribution bias by examining child emotional reactivity as a moderator. In addition, the differential impact of physical and psychological aggression was examined, as well as the relevance of this process for boys and girls. One hundred and five children were assessed at 7.5- and 10.5-years on measures of parent-child hostile experiences, child emotional reactivity, and hostile attribution bias. Results indicated that emotional reactivity interacted with parent-child hostile experiences such that children with higher hostile experiences and low emotional reactivity evidenced higher hostile attributions relative to high emotionally reactive children. These findings were replicated for girls but not boys and for both psychological and physical parental aggression. Implications for further examination of the development of hostile attribution bias include examining cognitive functioning during hostile experiences and applying these results to interventions targeting victims of child abuse.